Classical discrete time frequency synthesizers employ a discrete time digital phase locked loop with a hybrid of digital and analog circuits. The analog circuits typically include a phase detector, an integrator, and a voltage controlled oscillator. Sink-source-float circuits are commonly used for phase detection. Sink-source-float phase detectors and analog integrators typically employ analog components such as capacitors, resistors, current sources and the like.
Depending on system requirements, these external components may need to be specialized so that they satisfy stringent temperature invariant and low leakage requirements which are necessary for proper operation of the phase locked loop. These components are often expensive to manufacture, and more importantly, often adversely affect the manufacturing quality of communication devices utilizing them.
Discrete time digital phase locked loops also often use digital signal processors in implementing digital signal processing algorithms such as a lead-lag network filter. An approach such as this is costly, and inefficient in power consumption.
Thus, what is needed is an apparatus for providing a discrete time digital phase locked loop which is cost effective, low in power consumption, and improves manufacturing quality.